GENERAL OBJECTIVES: To determine the long-range hazard, in terms of carcinogenesis, of radiotherapy and of chemotherapy used in treatment of Hodgkin's disease. SPECIFIC AIMS: (1) To determine the incidence of second primary malignancies in patients treated with modern modalities for primary Hodgkin's disease. (2) To determine the variation in incidence of second primary malignancies by modality of therapy for primary Hodgkin's disease, comparing: (a) Non-intensive radiotherapy; (b) Intensive radiotherapy; (c) Non-intensive chemotherapy; (d) Intensive chemotherapy; (e) Radiotherapy followed by chemotherapy; (f) Chemotherapy followed by radiotherapy. (3) To determine the variation in incidence of second primary malignancies by time since initiation of therapy for Hodgkin's disease. (4) To determine the distribution by organ site of second primary malignancies. METHODS: A cohort study is planned, using retrospective data on patients treated in 1960 to 1976 and followed to 1976 or death before 1976 and using prospective data on these same patients followed to 1980 and on patients newly treated after 1976 and followed to 1980. Patients with Hodgkin's disease will be ascertained through registration records of large cancer therapy centers. It is planned to enroll approximately 100 newly registered patients per year for the registration years 1960 to 1979, or a total of 2000 patients. The desired 100 patients for each registration year will be enrolled through collaboration of eight centers.